n marine benthic invertebrates with complex life cycles, recruitment success, juvenile survival, and growth may be affected by variation in both maternal factors and environmental conditions prevailing during preceding embryonic or larval development. In an estuarine crab, Chasmagnathus granulata, previous investigations have shown that initial larval biomass is positively correlated with the biomass of recently extruded eggs, and it depends also on the salinity experienced during embryogenesis. Biomass at hatching has consequences for the subsequent larval development which, in this species, comprises two alternative developmental pathways with four or five zoeal instars (short or long pathway; SP, LP) and a megalopa. Larvae hatching with a lower than average biomass, tend to develop through the LP and metamorphose to megalopae with higher biomass. In the present study, we show experimentally that the LP produces also significantly larger juveniles (crab size measured as carapace width, biomass as dry mass, carbon and nitrogen contents). Compared with juveniles originating from the SP, those from the LP showed in successive instars longer moulting cycles and larger carapace width, but lower size increments at ecdysis. In consequence, differences in size or biomass of LP vs. SP crabs tended to disappear in later instars (after stage V). Furthermore, we tested in juveniles the tolerance of starvation at three salinities (5, 15, 32). Tolerance of starvation was significantly higher in juveniles originating from the LP, indicating higher energy reserves. While salinity played only a minor role for survival, it exerted significant effects on the time of moulting to the second juvenile instar, regardless of the preceding developmental pathway. The biomass of first juveniles obtained from the SP showed a significant positive correlation with the biomass of the freshly hatched zoea I, but not in those from the LP. In conclusion, the fitness of juvenile C. granulata is linked with previous developmental processes and environmental conditions during the embryonic and larval phase. Hence, a better understanding and prediction of the recruitment success of marine benthic invertebrates with a complex life cycle may require more comprehensive life-history investigations.
Helmholtz Research Programs > MARCOPOLI (2004-2008) > CO2-Coastal diversity - key species and food webs